posted on Jul, 15 2008 @ 05:20 PM
, the primary advantage of the DIRECT design over NASA's current Ares I/V designs is that DIRECT retains more of existing STS
(Space Transportation System, commonly called the shuttle) infrastructure than either Ares vehicle.
NASA's baseline for the Ares vehicles calls for a re-designed 5.5 segment SRB (as opposed to the 4 segment SRBs used on STS) and separate launch
vehicles for crew (Ares I) and cargo (Ares V). Ares I will be powered by a single 5.5 segment SRB topped with a relatively small upper stage powered
by a J-2X rocket engine. Ares V will use 2 of the 5.5 segment SRBs strapped on either side of a 10-meter (diameter) LOX/LH2 core stage driven by 5
(possibly 6; there are unconfirmed reports that this aspect of the design is in flux) RS-68 rocket engines. Ares V will use an upper stage/Earth
Departure Stage (EDS) powered by a J-2X, although this upper stage is currently baselined at 10 meters in diameter and is NOT identical to the upper
stage used on Ares I, although both will use the same engine.
While the Ares V arrangement looks much like the current STS system, STS uses an 8.4 meter core, not the 10 meters Ares V is currently baselined at.
Ares will be much wider than the STS, necessitating changes to the tooling used to manufacture the core tank, changes to the barge used to transport
the tank from Louisiana (where it is manufactured) to the Vehicle Assembly Building in Florida, changes to the processing facilities in the Vehicle
Assembly Building, changes to the Mobile Launch Platforms which support the rocket during launch, changes to the crawlers used to transport the
platforms to the launch site, and changes to the launch sites themselves. Ares I would require entirely new infrastructure in the form of (at
absolute minimum) a new Mobile Launch Platform and changes to the launch site.
The DIRECT plan avoids the majority of those changes. Same sized tank means same sized tooling, using a physically identical/similar vehicle for crew
and cargo launches avoids the expense of keeping 2 production lines open, and existing Mobile Launch Platforms, Launch Pads, and
construction/transport (barge)/processing facilities can be used with very little modification.
NASA is reinventing the wheel with respect to the infrastructure changes inherent in their ARES designs. They're spending more money than is
necessary (and probably more money than they have/will have) on two rockets which are in danger of becoming too expensive to fly - the exact same
problem which killed the Saturn V and ended our FIRST manned moon program.
Information about the DIRECT launcher is available at the websites linked in my first post to this thread; information about the Ares launchers is
available from NASA at NASA's reference page